For example, in the pharmaceutical industry, preparative separation/purification systems utilizing liquid chromatographs are used to collect samples of a variety of chemically synthesized compounds in order to store those samples in a library or analyze them in more detail. Conventional examples of the preparative separation/purification system are disclosed in Patent Documents 1 and 2.
In these conventional apparatuses, target components (compounds) in a sample solution are temporally separated by a liquid chromatograph. The separated target components are then respectively introduced into different trap columns and temporarily captured therein. Subsequently, a solvent is supplied into each trap column to quickly elute the component from the trap column and collect it in a container. Thus, a plurality of solutions each containing one target component at a high concentration are respectively collected in a plurality of containers. These separately collected solutions are then subjected to a vaporizing and drying process to remove the solvent and collect the target components in solid forms. The vaporizing and drying process normally includes heating the collected solutions or centrifuging them under vacuum.
According to the aforementioned conventional method, however, a single vaporizing and drying process requires a long period of time of, for example, several hours to one day. In the pharmaceutical industry, various efforts have been made to, improve the efficiency of searching for a large number of synthetic compounds for medicinal compounds; for example, the analysis time has been reduced by using faster analysis apparatuses or optimizing the analytical methods. Reducing the time required for the vaporizing and drying process is a critical issue since this process consumes the longest time within the entire process.
One reason why a long period of time is required to vaporize the solvent from the eluate collected in the previously described manner is the presence of water included in the collected eluate. As the solvent for eluting target components captured in a trap column, an organic solvent is often used. As compared to water, organic solvents have much lower boiling points and hence are highly volatile. Therefore, when the target components are dissolved in a pure organic solvent, the vaporizing and drying process requires only a short period of time. On the other hand, if water, which is less volatile, is included in the solvent, the vaporizing and drying process takes a considerable length of time.
In the capturing process using the trap column, the target component is introduced into the trap column with the mobile phase of the preparative liquid chromatograph. In many cases, the mobile phase consists of either water or an aqueous solvent containing water as the main component. In these cases, a certain amount of water remains in the trap column at the completion of capturing the target component. This problem also arises in the widely used technique of introducing water into the passage of the mobile phase at a location before the trap column in order to dilute the mobile phase with water and thereby reduce the elution power of the mobile phase so that the target component can be assuredly captured. In this case, the water remains in the trap column at the completion of capturing the target component. Furthermore, after the target component is captured, it is often necessary to wash the trap column by introducing water into it to remove unnecessary components other than the target one, such as the salts originating from the mobile phase, that are present within the trap column. In this case, the mobile phase in the trap column is replaced by water, so that the trap column becomes filled with the water.
For such a variety of reasons, in many cases, the trap column contains a considerable amount of water after the target component is captured. When such a large amount of water is present in the trap column, supplying an organic solvent into the trap column to elute the target component will naturally result in a large amount of remnant water to be included in the solution exiting from the trap column.
Patent Document 1: Japanese Unexamined Patent Application Publication No. H2-122260
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2003-149217